Ion-based methods for stabilizing and improving porous metal-organic framework (mof) materials for water harvesting from air and related applications

A method for harvesting water from an atmosphere containing vapor-phase water molecules using metal organic frameworks, the metal organic frameworks comprising:

• metal organic framework molecules having positively charged, linker unsaturated nodes and a net positive charge;
• and
• charge compensating anions that are not bonded to the linker unsaturated nodes via coordination bonds and that have freedom of motion through the pores of the metal organic framework,
• the method comprising:
• exposing the metal organic frameworks to the atmosphere at a temperature at which vapor-phase water molecules condense as liquid water within the pores of the metal organic framework molecules, wherein the water-soluble ions are solubilized by the liquid water;
• increasing the temperature of the metal organic frameworks to a temperature at which the water molecules are released from the pores of the metal organic framework molecules, decreasing the relative humidity of the atmosphere to a relative humidity at which the water molecules are released from the pores of the metal organic framework molecules, or both;
• and
• collecting the released water molecules.

A method of making charge-compensated metal organic frameworks, the method comprising:

• synthesizing metal organic framework molecules having linker unsaturated nodes and an initial set of ligands on the linker unsaturated nodes;
• dispersing the metal organic framework molecules in a solution comprising a salt that dissociates into cations and charge compensating anions, wherein the cations form coordination bonds to the linker unsaturated nodes to impart a net positive charge to the metal organic framework molecules, and the charge-compensating anions remain solvated;
• and
• separating the positively charged metal organic frameworks and the charge-compensating anions from the solution;
• and
• drying the metal organic framework molecules to provide charge-compensated metal organic frameworks comprising positively charged metal organic framework molecules and charge compensating anions dispersed within pores of the positively charged metal organic framework molecules.